1. Field of the Invention
The present invention relates to viewpoint detecting device.
2. Related Background Art
Imaging equipment such as video cameras have shown remarkable progress in recent years, toward a smaller size and more diversified functions.
Along with such progress, for the purpose of reducing the cumbersome operations associated with such diversified functions and of achieving the operation intended by the operator, there is being introduced the viewpoint detecting device enabling the execution of various functions and the control of various operations by viewpoint of the operator.
Such viewpoint detecting device, for example in case of a camera such as a video camera, enables focusing to a position watched by the operator or functions as a switch for executing any of the functions when a corresponding index mark is watched by the operator.
In the following there will be explained an example of the video camera in which the viewpoint detecting device is utilized for lens focusing and zooming.
The viewpoint detecting device, conventionally equipped in the video camera or the like, has the viewpoint input functions for effecting the zooming operation by selecting zooming marks "TELE" and "WIDE" displayed on the image area of the view finder with the viewpoint and the focusing operation at the watched position of said image area.
FIG. 1 is a schematic block diagram of a video camera with viewpoint switching function.
The video camera shown in FIG. 1 is provided with a phototaking lens system 1 including a zoom lens for taking the image of an object; a view finder 3 containing a finder image area 2 for observing the object to be taken by the phototaking lens system 1; an eyepiece lens 4 provided in front of the view finder 3; viewpoint detection means 6 for detecting the viewpoint of an eye 5 of the photographer; a display circuit 7 for displaying, on the image area 2, an AF frame approximately showing the focusing area, viewpoint switch marks to be explained later and other information such as tape counter and phototaking mode, required for the photographer; a system control circuit 8 for controlling various parts of the camera; a memory 9 for memorizing the coordinate values of the viewpoint switch marks on the finder image area; and an adder 10 for the outputs of the phototaking lens system 1 and the display circuit 7.
The above-mentioned viewpoint detecting means 6 is provided with an infrared light emitting diode 60 for irradiating the eye 5 of the photographer with infrared light; a dichroic mirror 61 transmitting the visible light but reflecting the infrared light; a condenser lens 62 for condensing the infrared light reflected by said dichroic mirror 61; a photoelectric converting element 63 for converting the infrared light, condensed by said condenser lens 62, into an electrical signal; and a viewpoint detecting circuit 64 for determining the point watched by the photographer on the finder image area, based on the image of the eye 5 of the photographer on said photoelectric converting element 63.
As the dichroic mirror 61 transmits the visible light, the photographer can observe the finder image area 2 through the eyepiece lens 4. Also as the dichroic mirror 61 reflects the infrared light, the reflected image of the eye 5, irradiated by the infrared light emitting diode 60, is condensed by the condenser lens 62 and focused on the photoelectric converting element 63.
The viewpoint detecting circuit 64 determines the viewpoint of the photographer on the finder image area 2, based on the image of the eye 5 on the photoelectric converting element 63, according to the above-mentioned principle or an algorithm disclosed in the Japanese Patent Laid-open Application Nos. 1-241511 and 2-32312.
In the following there will be explained the functions of the viewpoint switch provided in the view finder of the present conventional video camera.
An example of the display on the finder image area is schematically shown in FIG. 2.
On the finder image area 100, there is displayed a menu consisting of index marks 1a, 1b represented by letters "W" and "T" and indicating mutually different operations. For example "W" indicates the zooming operation toward the wide angle side, while "T" indicates that toward the telephoto side. A numeral "902" at the lower right corner indicates, for example, a date.
Now reference is made to a flow chart shown in FIG. 3, for explaining the zooming operation utilizing the viewpoint detection. Groups of coordinates of predetermined ranges including the visual switch index marks are memorized in a memory, and each group includes all the coordinates within the range of each index mark shown in FIG. 2. These groups are represented for example by .alpha. and .beta. respectively for the wide angle side and the telephoto side. At first, when the power supply to the video camera is turned on (step S1), variables l and m are reset to zero (step S2), whereby the viewpoint switches are made ready. The variables l, m respectively indicate the numbers of coincidences of the watching point of the photographer with any of the coordinates of the groups .alpha. and .beta.. While the photographer looks into the view finder and the viewpoint detection is executed properly (step S3), the system control circuit 8 continuously receives the coordinate of the watching point of the photographer on the finder image area from the viewpoint detecting means 6.
In the following there will be explained, as an example, the functions when the photographer watches the wide angle index mark "W" in the finder image area. When the coordinate of the viewpoint coincides with any of the coordinates in the group .alpha. (step S4), the system control circuit 8 terminates any function other than the zooming operation toward the wide angle side (S6), then resets the variable m to 0 (S5), discriminates whether the variable l is equal to or larger than a predetermined number (5 in the present example) (S6), and, if less, adds 1 to l (S8). Then there is again discriminated whether l is equal to or larger than 5 (S9), and, if less, the sequence returns to the step S3 to receive the coordinate of the viewpoint from the viewpoint detecting circuit 64.
On the other hand, if the step S9 identifies that l is equal to or larger than 5, the zoom lens is shifted toward the wide angle side, and the sequence then returns to the step S3 to receive the coordinate of the viewpoint again. If the step S6 identifies that l is equal to or larger than 5, the sequence jumps to a step S11. Even when the coordinate of the viewpoint coincides with any of the coordinates in the group .alpha., if the coordinate of the viewpoint moves outside the group .alpha. before the number of coincidences reaches 5, the variable l is reset to zero (steps S13, S28). When the index mark "T" is looked at, a similar procedure is also executed.
In the above-explained configuration, however, the photographer is required to continue to look at the mark "W" for zooming toward the wide angle side or the mark "T" for zooming toward the telephoto side until the image angle reaches a value desired by the photographer by the zooming, so that the photographer becomes tired.
The above-mentioned drawback is not limited to the zooming operation but is associated with any analog adjustment of the function, and is commonly encountered in a control system utilizing the viewpoint detecting device.